An acid etch, resin technique has been proposed for conservatively restoring cervical erosion lesions. Little is known about the micromorphologic features of these lesions as they affect dentin and pulp. The objective will be to determine the histologic features of: 1) surface of the lesion, 2) changes within the dentin, 3) the type of reparative dentin, and 4) pulp changes. In addition, the morphologic features of acid conditioned, eroded dentin and its appearance after placement of N-phenyl glycine-glycidyl methacrylate (NPG-GMA) will be determined along with the physical relationship between such treated surfaces and composite resin. The determinations will be made using light and scanning electron microscopy and contact microradiography.